Ultrasonic surgical blade and instrument having a gain step

ABSTRACT

An ultrasonic surgical blade, and an instrument, having a gain step. The blade body has, in any half wave length of the ultrasonic-surgical-blade body, a first vibration antinode, a vibration node, a second vibration antinode, and a gain step. The gain step is located between the second vibration antinode and the first vibration antinode. The gain step is spaced apart from the vibration node by a gain-step distance greater than 5% of the distance between the second vibration antinode and the first vibration antinode. The instrument includes the blade, a handpiece having an ultrasonic transducer, and an ultrasonic transmission rod whose proximal end is operatively connected to the ultrasonic transducer and whose distal end activates the blade. In one option, the first vibration antinode is the distal tip, and the gain step is located between the vibration node and the distal tip, resulting in an increased active length of the blade.

RELATED APPLICATIONS

The application is a continuation of U.S. patent application, Ser. No.10/701,588, filed on Nov. 5, 2003.

FIELD OF THE INVENTION

The present invention relates generally to ultrasonic surgical bladesand ultrasonic surgical instruments which include ultrasonic surgicalblades, and more particularly to those having a gain step.

BACKGROUND OF THE INVENTION

Ultrasonic surgical instruments are known which include ultrasonicsurgical blades. A handpiece of a known ultrasonic surgical instrumentincludes an ultrasonic transducer which is powered by an ultrasonicgenerator through a cable. An ultrasonic transmission rod of theinstrument has a proximal end and a distal end, wherein the proximal endis operatively connected to the ultrasonic transducer. An ultrasonicsurgical blade is activated by the distal end of the ultrasonictransmission rod. Known blade shapes include straight blades andasymmetric about a longitudinal axis or about a curved centerline of theblade.

A known ultrasonic surgical blade is a cylindrical blade which has adistal tip, a most-distal vibration node (a vibration node being a pointof substantially zero displacement), and a second most-distal vibrationantinode (a vibration antinode being a point of maximum displacementrelative to all other points in a half wave), wherein the most-distalvibration antinode is the distal tip. Longitudinal ultrasonic vibrationof the blade generates motion and heat in the contacted tissue, whereinthe heat primarily provides the means for the blade to cut and/orcoagulate patient tissue. The blade has a gain step located a distancefrom the most-distal vibration node which is less than 5% of thedistance between the distal tip and the second-most-distal vibrationantinode because locating the gain step close to the most-distalvibration node maximizes the vibration amplitude gain. The known bladeconsists of a larger-diameter right-circular geometrically-solidcylinder from the second most-distal vibration antinode to themost-distal vibration node. The known blade consists of asmaller-diameter right-circular geometrically-solid cylinder from themost-distal vibration node to the distal tip. The change in diameterprovides a gain in vibration amplitude for the smaller-diameter sectionof the blade equal to the ratio of the transverse cross-sectional areasof the larger diameter blade section to the smaller diameter bladesection when the gain step is located at the node.

The active length of an ultrasonic surgical blade is defined byapplicants as the distance from the distal tip to where the vibrationamplitude (i.e., the longitudinal vibration amplitude) has fallen to 50%of the tip amplitude. The blade is not considered useful beyond itsactive length. The active length is about 15 mm for a straightcylindrical titanium rod at a resonant frequency of about 55.5 kHz.

It is known in ultrasonic welding of plastics to provide an ultrasonicwelding rod having a gain step, such as a discontinuity between a largerand a smaller rod diameter, which is located between the most-distalvibration node and the distal end of the welding horn and which isspaced apart from the most-distal vibration node of the welding rod by adistance less than 5% of the distance between the second-most-distalvibration antinode and the distal end of the welding rod. It is alsoknown in ultrasonic welding of plastics to provide an ultrasonic weldingrod with a hole or a slot to provide a gain in longitudinal vibrationamplitude.

What is needed is an improved ultrasonic surgical blade, and an improvedultrasonic surgical instrument which includes an ultrasonic surgicalblade, having a longer or shorter active length.

SUMMARY OF THE INVENTION

A first expression of an embodiment of the invention is for anultrasonic surgical blade including an ultrasonic-surgical-blade body.The ultrasonic-surgical-blade body has a distal tip which is amost-distal vibration antinode, has a most-distal vibration node, has asecond-most-distal vibration antinode, and has a gain step. The gainstep is located between the second-most-distal vibration antinode andthe distal tip, and the gain step is spaced apart from the most-distalvibration node by a gain-step distance greater than 5% of the distancebetween the second-most-distal vibration antinode and the distal tip.

A second expression of an embodiment of the invention is for anultrasonic surgical instrument including a handpiece, an ultrasonictransmission rod, and an ultrasonic surgical blade. The handpieceincludes an ultrasonic transducer. The ultrasonic transmission rod has aproximal end and a distal end, wherein the proximal end is operativelyconnected to the ultrasonic transducer. The ultrasonic surgical blade isactivated by the distal end and includes an ultrasonic-surgical-bladebody. The ultrasonic-surgical-blade body has a distal tip which is amost-distal vibration antinode, has a most-distal vibration node, has asecond-most-distal vibration antinode, and has a gain step. The gainstep is located between the second-most-distal vibration antinode andthe distal tip, and the gain step is spaced apart from the most-distalvibration node by a gain-step distance greater than 5% of the distancebetween the second-most-distal vibration antinode and the distal tip.

A third expression of an embodiment of the invention is for anultrasonic surgical blade including an ultrasonic-surgical-blade body.The ultrasonic-surgical-blade body has, in any half wave length of theultrasonic-surgical-blade body, a first vibration antinode, a vibrationnode, a second vibration antinode, and a gain step. The gain step islocated between the second vibration antinode and the first vibrationantinode. The gain step is spaced apart from the vibration node by again-step distance greater than 5% of the distance between the secondvibration antinode and the first vibration antinode.

Several benefits and advantages are obtained from one or more of theexpressions of the embodiment of the invention. Applicants found thatlocating a gain step having a gain greater than unity (i.e., anamplification step) further than conventionally taught from themost-distal vibration node toward the distal tip further increased theactive length of the ultrasonic surgical blade even though the vibrationamplitude gain was less than when conventionally locating the gain stepcloser to the most-distal vibration node. Applicants determined thatlocating the gain step further than conventionally taught from themost-distal vibration node toward the second-most-distal vibrationantinode should shorten the half wave length of the ultrasonic surgicalblade. Applicants also determined that such changes in active and halfwave lengths of the ultrasonic surgical blade would also result fromgain steps having gains less than unity (i.e., a deamplification step)but with a deamplification step causing a decrease in active lengthwhere an identically located amplification step would cause an increasein active length and with a deamplification step causing an increase inactive length where an identically located amplification step wouldcause a decrease in active length. Being able to lengthen or shorten theactive length of an ultrasonic surgical blade offers advantages forparticular surgical applications, as can be appreciated by those skilledin the art.

The present invention has, without limitation, application inrobotic-assisted surgery.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of a first embodiment of an ultrasonicsurgical instrument including a first embodiment of an ultrasonicsurgical blade of the invention;

FIG. 2 is a longitudinal cross-sectional view of the most-distalone-half wavelength, including the distal tip, of the ultrasonicsurgical blade of FIG. 1;

FIG. 3 is a longitudinal cross-sectional view of the most-distalone-half wavelength, including the distal tip, of a second embodiment ofthe surgical blade of FIG. 1; and

FIG. 4 is a longitudinal cross-sectional view of the most-distalone-half wavelength, including the distal tip, of a third embodiment ofthe surgical blade of FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION

Before explaining the present invention in detail, it should be notedthat the invention is not limited in its application or use to thedetails of construction and arrangement of parts illustrated in theaccompanying drawings and description. The illustrative embodiment ofthe invention may be implemented or incorporated in other embodiments,variations and modifications, and may be practiced or carried out invarious ways. Furthermore, unless otherwise indicated, the terms andexpressions employed herein have been chosen for the purpose ofdescribing the illustrative embodiment of the present invention for theconvenience of the reader and are not for the purpose of limiting theinvention.

It is understood that any one or more of the following-describedexpressions of an embodiment, examples, etc. can be combined with anyone or more of the other following-described expressions of anembodiment, examples, etc. For example, and without limitation, a gainfeature of a reduced diameter can be combined with a gain feature of ahole.

Referring now to the drawings, FIGS. 1-2 illustrate a first embodimentof the invention. A first expression of the first embodiment of FIGS.1-2 is for an ultrasonic surgical blade 10 including anultrasonic-surgical-blade body 12 having a distal tip 14 which is amost-distal vibration antinode (a vibration antinode being a point ofmaximum displacement relative to all other points in a half wave),having a most-distal vibration node 16 (a vibration node being a pointof substantially zero displacement), having a second-most-distalvibration antinode 18, and having a gain step 20. The gain step 20 isdisposed between the second-most-distal vibration antinode 18 and thedistal tip 14 and is spaced apart from the most-distal vibration node 16by a gain-step distance 22 greater than 5% of the distance 24 betweenthe second-most-distal vibration antinode 18 and the distal tip 14.

In one implementation of the first expression of the first embodiment ofFIGS. 1-2, the gain step distance 22 is between substantially 25% andsubstantially 45% of the distance 24 between the second-most-distalvibration antinode 18 and the distal tip 14. Those of ordinary skill inthe art, employing the teachings of the invention for the location ofthe gain step 20, can create analytical blade models and evaluate themusing a computer program to optimize design trade-offs between increasedor decreased active length of the ultrasonic surgical blade andincreased or decreased amplitude of the longitudinal ultrasonicvibrations for locating the gain step 20 substantially away from themost-distal vibration node 16 in the direction of the distal tip 14 orin the direction of the second-most-distal vibration antinode 18.

In one example of the first expression of the first embodiment of FIGS.1-2, between the second-most-distal vibration antinode 18 and the distaltip 14, the maximum vibration amplitude of the ultrasonic-surgical-bladebody 12 proximal the gain step 20 is less than the maximum vibrationamplitude of the ultrasonic-surgical-blade body 12 distal the gain step20. In this example, the gain of the gain step 20 is greater than unityand results from a reduction in mass of the ultrasonic-surgical-bladebody 12 between the gain step 20 and the distal tip 14 compared to themass of the ultrasonic-surgical-blade body 12 between the gain step 20and the second-most-distal vibration antinode 18.

In a different embodiment, not shown, between the second-most-distalvibration antinode and the distal tip, the maximum vibration amplitudeof the ultrasonic-surgical-blade body proximal the gain step is greaterthan the maximum vibration amplitude of the ultrasonic-surgical-bladebody distal the gain step. In this embodiment, the gain of the gain stepis less than unity and results from an increase in mass of theultrasonic-surgical-blade body between the gain step and the distal tipcompared to the mass of the ultrasonic-surgical-blade body between thegain step and the second-most-distal vibration antinode. This embodimentcan be easily visualized, in one example, by switching the locations ofthe distal tip 14 and the second-most-distal vibration antinode 18 inFIG. 2.

In one enablement of the first expression of the first embodiment ofFIGS. 1-2, the gain step 20 is disposed between the most-distalvibration node 16 and the distal tip 14 resulting in an increased activelength of the ultrasonic surgical blade 10. In a different embodiment,not shown, the gain step is disposed between the most-distal vibrationnode and the second-most-distal vibration antinode resulting in adecreased half wave length of the ultrasonic surgical blade. Thisembodiment can be easily visualized by moving the gain step 20 betweenthe most-distal vibration node 16 and the second-most-distal vibrationantinode 18 in FIG. 2.

In one illustration of the first expression of the first embodiment ofFIGS. 1-2, the ultrasonic-surgical-blade body 12 has a longitudinal axis26 and consists essentially of a first geometric solid 28 having asubstantially constant first transverse cross-sectional area from thegain step 20 to the distal tip 14 and a second geometric solid 30 havinga substantially constant second transverse cross-sectional area from thegain step 20 to the second-most-distal vibration antinode 18. The secondtransverse cross-sectional area is different than the first transversecross-sectional area. In one variation, the shape and size of the firstexternal perimeter of the first transverse cross-sectional area issubstantially equal to the shape and size of the second externalperimeter of the second transverse cross-sectional area. In onemodification, at least one of the first and second transversecross-sectional areas surrounds a void 32. In one construction, the void32 includes a first longitudinal hole 34 which is disposed in the firstgeometric solid 28 and which extends proximally from the distal tip 14.Applicants found that locating the gain step 20 at the point where thegain equaled the square root of the ratio of the transversecross-sectional areas of the second geometric solid 30 to the firstgeometric solid 28 optimized the increase in the active length of theblade. In one arrangement, the void 32 includes a second longitudinalhole 36 which is disposed in the second geometric solid 30 and which isin fluid communication with the first longitudinal hole 34, and thefirst and second longitudinal holes 34 and 36 are adapted for irrigationand/or suction. In another arrangement, the ultrasonic surgical blade 10also includes a membrane 38 which has a composition substantially thesame as the composition of the ultrasonic-surgical-blade body 12, whichcovers the first longitudinal hole 34, and which is removably orpermanently attached to the first geometric solid 28 at the distal tip14. It is noted that the membrane 38 would be removed from the firstgeometric solid 28 in FIG. 2 when irrigation and/or suction is desired.Alternatively, membrane 38 may be made from a permeable fabric, such asa wire mesh or screen, or sintered mesh made from titanium or otherappropriate material to facilitate irrigation and/or suction.

In a different embodiment, not shown, the ultrasonic-surgical-blade bodyhas a longitudinal axis and consists essentially of a first geometricsolid and a second geometric solid. The first geometric solid has afirst mass, extends from the gain step to the distal tip, and has anon-constant first transverse cross-sectional area. The second geometricsolid has a second mass, extends from the gain step to thesecond-most-distal vibration antinode, and has a non-constant secondtransverse cross-sectional area. The second mass is different than thefirst mass. This embodiment is easily visualized, in one example, byconsidering the second longitudinal hole 36 to have a diameter whichdecreases from the second-most-distal vibration antinode 18 to the gainstep 20 and the first longitudinal hole 34 to have a diameter whichincreases from the gain step 20 to the distal tip 14 in FIG. 2. Thevariations, modifications, etc. of the preceding paragraph are equallyapplicable to this embodiment.

In a further embodiment, not shown, the ultrasonic surgical blade bodyhas a longitudinal axis and consists essentially of a first geometricsolid having a first mass and having a first axial length extending fromthe gain step to the distal tip and a second geometric solid having asecond mass and having a second axial length extending from the gainstep to the second-most-distal vibration antinode. The second mass isdifferent than the first mass. One of the first and second geometricsolids has a substantially constant transverse cross-sectional areaalong its corresponding axial length, and a different one of the firstand second geometric solids has a non-constant transversecross-sectional area along its corresponding axial length. Thisembodiment is easily visualized, in one example, by considering thefirst longitudinal hole 34 to have a diameter which increases from thegain step 20 to the distal tip 14 in FIG. 2. The variations,modifications, etc. of the second preceding paragraph are equallyapplicable to this embodiment.

In one design of the first expression of the first embodiment of FIGS.1-2, the ultrasonic-surgical-blade body 12 has a longitudinal axis 26and is substantially symmetrical about the longitudinal axis 26. Inanother design, not shown, the ultrasonic-surgical-blade body has alongitudinal axis, has an active length, and is substantially asymmetricabout the longitudinal axis along at least a portion of the activelength. In one variation, the ultrasonic-surgical-blade body is curved.This variation is easily visualized, in one example, by curving thedistal portion of the ultrasonic-surgical-blade body 12 upward from thelongitudinal axis 26 in FIG. 2.

In one deployment of the first expression of the first embodiment ofFIGS. 1-2, the ultrasonic-surgical-blade body 12 has at least one gainfeature 40 selected from the group consisting of: a discrete change inouter diameter or perimeter, a taper, a longitudinal hole, a discretechange in diameter of a longitudinal hole, a transverse hole, a surfaceflat, and a surface slot. It is noted that, in this deployment, the gainstep 20 is the location of the portion of the gain feature 40 which isclosest to the most-distal vibration node 16. It is also noted that theterm “hole” includes a through hole and a non-through hole. Other gainfeatures are left to the artisan.

FIG. 3 illustrates a second embodiment of the ultrasonic surgical blade110 of the invention. In this embodiment, the ultrasonic-surgical-bladebody 112 has an additional gain step 142 which is spaced-apart from thegain step 120, which is disposed between the second-most-distalvibration antinode 118 and the distal tip 114, and which is spaced apartfrom the most-distal vibration node 116 by a gain-step distance 122greater than 5% of the distance 124 between the second-most-distalvibration antinode 118 and the distal tip 114. Theultrasonic-surgical-blade body 112 has a longitudinal axis 126 and alongitudinally hole 134, wherein the longitudinal hole has a shoulder144 defining the additional gain step 142.

A third embodiment of an ultrasonic surgical blade 210 is shown in FIG.4, wherein the ultrasonic-surgical-blade body 212 consists essentiallyof a right-circular first geometrically-solid cylinder 288 from the gainstep 220 to the distal tip 214. In this embodiment, theultrasonic-surgical-blade body 212 consists essentially of aright-circular second geometrically-solid cylinder 230 from the gainstep 220 to the second-most-distal vibration antinode 218. The diameterof the first geometrically-solid cylinder 288 is less than the diameterof the second geometrically-solid cylinder 230. It is noted that in thisembodiment, the gain feature 240 is a reduced diameter from the distaltip 214 to the gain step 220 which reduces mass and which creates thefirst geometrically-solid cylinder 288. The gain step 220 is disposedbetween the second-most-distal vibration antinode 218 and the distal tip214 and is spaced apart from the most-distal vibration node 216 by again-step distance 222 greater than 5% of the distance 224 between thesecond-most-distal vibration antinode 218 and the distal tip 214.

In one construction of the first expression of the first embodiment ofFIGS. 1-2, the ultrasonic-surgical-blade body 12 consists essentially oftitanium. In other constructions, blade bodies consist essentially ofaluminum, a ceramic, sapphire, or any other material that transmitsultrasound in an efficient manner. Mathematical analysis of varioustitanium blade designs using the described principles of the inventioncalling for locating the gain step 20 substantially away from themost-distal vibration node 16 in the direction of the distal tip 14achieved increases in the active length of the ultrasonic surgical blade10 up to 40%. Applicants have seen increases up to 60% in theory. Aspreviously mentioned, the active length of an ultrasonic surgical blade10 is defined as the distance from the distal tip 14 to where thevibration amplitude (i.e., the longitudinal vibration amplitude) hasfallen to 50% of the tip amplitude. The blade is not considered usefulbeyond its active length. The active length is about 15 mm for astraight cylindrical titanium rod at a resonant frequency of about 55.5kHz without applying the principles of the invention. An increase inactive length up to about 5 mm can be expected using the describedprinciples of the invention when the gain step 20 is disposed betweenthe most-distal vibration node 16 and the distal tip 14.

In one arrangement, the ultrasonic surgical blade 10 is used alone asthe end effector of an ultrasonic surgical instrument. In anotherarrangement, the ultrasonic surgical blade 10 is used with a clamp arm(not shown) to create a shears end effector of an ultrasonic surgicalinstrument for cutting and/or coagulating patient tissue.

A second expression of the first embodiment of FIGS. 1-2 is for anultrasonic surgical instrument 46 including a handpiece 48, anultrasonic transmission rod 50, and an ultrasonic surgical blade 10. Thehandpiece 48 includes an ultrasonic transducer 52. The ultrasonictransmission rod 50 has a proximal end and a distal end, wherein theproximal end is operatively connected to the ultrasonic transducer 52.The ultrasonic surgical blade 10 is activated by the distal end andincludes an ultrasonic-surgical-blade body 12. Theultrasonic-surgical-blade body 12 has a distal tip 14 which is amost-distal vibration antinode, has a most-distal vibration node 16, hasa second-most-distal vibration antinode 18, and has a gain step 20. Thegain step 20 is disposed between the second-most-distal vibrationantinode 18 and the distal tip 14 and is spaced apart from themost-distal vibration node 16 by a gain-step distance 22 greater than 5%of the distance 24 between the second-most-distal vibration antinode 18and the distal tip 14.

In one enablement of the second expression of the first embodiment ofFIGS. 1-2, there is also included an ultrasonic generator 54, activatedby a foot pedal 56, and a cable 58 operatively connecting the ultrasonicgenerator 54 and the ultrasonic transducer 52 of the handpiece 48. Inone construction, the ultrasonic surgical blade 10 is a monolithicportion of the ultrasonic transmission rod 50. In another construction,the ultrasonic surgical blade is a separate piece and is attached to theultrasonic transmission rod. It is noted that the embodiments,implementations, examples, illustrations, etc. previously described forthe ultrasonic surgical blade are equally applicable to the ultrasonicsurgical instrument.

A third expression of the first embodiment of FIGS. 1-2 is for anultrasonic surgical blade including an ultrasonic-surgical-blade bodyhaving, in any half wave length of the ultrasonic-surgical-blade body, afirst vibration antinode, a vibration node, a second vibration antinode,and a gain step, wherein the gain step is disposed between the secondvibration antinode and the first vibration antinode, and wherein thegain step is spaced apart from the vibration node by a gain-stepdistance greater than 5% of the distance between the second vibrationantinode and the first vibration antinode. It is noted that the thirdexpression does not limit the location of the half wave to the last halfwave length of the blade body as with the previously presented secondexpression, and that apart from the second expression's location of thehalf wave, the embodiments, implementations, examples, illustrations,etc. previously described for the second expression are equallyapplicable to the third expression.

Several benefits and advantages are obtained from one or more of theexpressions of the embodiment of the invention. Applicants found thatlocating a gain step having a gain greater than unity (i.e., anamplification step) further than conventionally taught from themost-distal vibration node toward the distal tip further increased theactive length of the ultrasonic surgical blade even though the vibrationamplitude gain was less than when conventionally locating the gain stepcloser to the most-distal vibration node. Applicants determined thatlocating the gain step further than conventionally taught from themost-distal vibration node toward the second-most-distal vibrationantinode should shorten the half wave length of the ultrasonic surgicalblade. Applicants also determined that such changes in active and halfwave lengths of the ultrasonic surgical blade would also result fromgain steps having gains less than unity (i.e., a deamplification step)but with a deamplification step causing a decrease in active lengthwhere an identically located amplification step would cause an increasein active length and with a deamplification step causing an increase inactive length where an identically located amplification step wouldcause a decrease in active length. Being able to lengthen or shorten theactive length of an ultrasonic surgical blade offers advantages forparticular surgical applications, as can be appreciated by those skilledin the art.

The foregoing description of several expressions and embodiments of theinvention has been presented for purposes of illustration. It is notintended to be exhaustive or to limit the invention to the precise formsdisclosed, and obviously many modifications and variations are possiblein light of the above teaching. For example, as would be apparent tothose skilled in the art, the disclosures herein of the ultrasonicsurgical blade and ultrasonic surgical instrument have equal applicationin robotic assisted surgery taking into account the obviousmodifications of such systems, components and methods to be compatiblewith such a robotic system.

1. An ultrasonic surgical blade comprising an ultrasonic-surgical-blade body having a longitudinal axis, having a distal tip which is a most-distal vibration antinode, having a most-distal vibration node, having a second-most-distal vibration antinode, and having a gain step, wherein the longitudinal axis consists essentially of a first geometric solid having a substantially constant first transverse cross-sectional area from the gain step to the distal tip and a second geometric solid having a substantially constant second transverse cross-sectional area from the gain step to the second-most-distal vibration antinode wherein at least one of the first and second transverse cross-sectional areas surrounds a void.
 2. The ultrasonic surgical blade of claim 1, wherein the second transverse cross-sectional area is different than the first transverse cross-sectional area.
 3. The ultrasonic surgical blade of claim 1, wherein the void includes a first longitudinal hole which is disposed in the first geometric solid and which extends proximally from the distal tip.
 4. The ultrasonic surgical blade of claim 3, wherein the void includes a second longitudinal hole which is disposed in the second geometric solid and which is in fluid communication with the first longitudinal hole, and wherein the first and second longitudinal holes are adapted for irrigation and/or suction.
 5. The ultrasonic surgical blade of claim 3, also including a membrane, which covers the first longitudinal hole, and which is removably or permanently attached to the first geometric solid at the distal tip.
 6. The ultrasonic surgical blade of claim 1, wherein the first geometric solid has a first mass, extends from the gain step to the distal tip, and has a non-constant first transverse cross-sectional area, wherein the second geometric solid has a second mass, extends from the gain step to the second-most-distal vibration antinode, and has a non-constant second transverse cross-sectional area, and wherein the second mass is different than the first mass.
 7. The ultrasonic surgical blade of claim 6, wherein the shape and size of the first external perimeter of the first transverse cross-sectional area is substantially equal to the shape and size of the second external perimeter of the second transverse cross-sectional area.
 8. The ultrasonic surgical blade of claim 7, wherein at least one of the first and second transverse cross-sectional areas surrounds a void.
 9. The ultrasonic surgical blade of claim 8, wherein the void includes a first longitudinal hole which is disposed in the first geometric solid and which extends proximally from the distal tip.
 10. The ultrasonic surgical blade of claim 9, wherein the void includes a second longitudinal hole which is disposed in the second geometric solid and which is in fluid communication with the first longitudinal hole, and wherein the first and second longitudinal holes are adapted for irrigation and/or suction.
 11. The ultrasonic surgical blade of claim 9, also including a membrane, which covers the first longitudinal hole, and which is removably or permanently attached to the first geometric solid at the distal tip.
 12. The ultrasonic surgical blade of claim 1, wherein the ultrasonic-surgical-blade body has a longitudinal axis, has an active length, and is substantially asymmetric about the longitudinal axis along at least a portion of the active length.
 13. The ultrasonic surgical blade of claim 12, wherein the ultrasonic-surgical-blade body is curved. 